I use Atlas,the older style and also the newer ones. The older ones are a REAL MESS as they have to be "slammed" together to couple. I have a few Kadees,the 740s. I'm trying to convert to Protocraft for the ultimate in realism and the single and double shelf couplers from Jimmy Booth which is the Protocraft coupler only with safety shelves on,which were used from 1978 onwards. I've found all couple with each other and seem to work ok on larger curves. To couple requires opening the Protocraft knuckle for best results and then push the knuckle of the Atlas or Kadee ,whichever your coupling up to,so the knuckle of the Kadee or Atlas coupler is firmly closed grasping the Protocraft knuckle,otherwise the cars don't couple. Sometimes a Kadee will couple to the Protocraft without the Protocraft's knuckle being opened,but find this to be the exception and not the rule.
I'm using everything I can until,in the year 3535,(LOL),I can afford to fit all my rolling stock and diesels with the Protocraft type couplers. I like to do all my coupling and switching,including groundthrows on my turnouts,as close to prototype practices as possible.
Hope this helps.
As Always,
Al Hummel
